Before coming to law school, I only had a vague understanding of what the public domain was. Mostly, it seemed like a phrase people would throw around when describing music that was insanely old. However, a few of my friends make music in their spare time and seeing how they used music they found within the public domain” helped me understand its importance and how it functions.
Using the internet, my friend would find songs that were in the public domain. He would slice and dice particular sections from them. He would then add the sounds into his own sound mix, often changing the pitch and adding effects as he went along. The final product would sound unrecognizable, and usually really cool. (If you want an example of how musicians do this, this link offers some excellent examples of how to use public domain music. It also has a sound example that shows the unique sound a sample creates).